What type of research involves direct interaction with participants to gather data?

The type of research that involves direct interaction with participants to gather data is interviews. In interviews, researchers engage with individuals one-on-one, allowing them to explore participants' thoughts, experiences, and perspectives in depth. This direct interaction facilitates a rich collection of qualitative data, where the researcher can ask follow-up questions, clarify responses, and delve into complex topics that may not emerge through other methods.

Surveys, while also a method for gathering data, typically rely on structured questions answered by participants without real-time interaction. Case studies involve a comprehensive analysis of a particular instance or example, often utilizing multiple data sources, but they are not inherently focused on direct participant interaction in the same way that interviews are. The Delphi technique is characterized by structured communication with a panel of experts, usually through rounds of questionnaires, rather than through direct, personal interactions. Thus, interviews distinctly represent the approach of engaging directly with individuals for the purpose of gathering data.